Property, Plant and Equipment - Schedule of Mineral Property Expenditures (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Total expense for the period	$ 3,502	$ 5,215
Kingsville Dome Project [Member]
Total expense for the period	862	2,378
Rosita Project [Member]
Total expense for the period	817	508
Vasquez Project [Member]
Total expense for the period	518	120
Alta Mesa Este Exploration Project [Member]
Total expense for the period	11
Butler Ranch Exploration Project [Member]
Total expense for the period	32
Sejita Dome Exploration Project [Member]
Total expense for the period
Crownpoint Project [Member]
Total expense for the period	5	268
Churchrock Project [Member]
Total expense for the period	109	250
Cebolleta Property [Member]
Total expense for the period	571	585
Juan Tafoya Property [Member]
Total expense for the period	413	474
Roca Honda Project [Member]
Total expense for the period	80	75
Nose Rock Project [Member]
Total expense for the period
West Largo Project [Member]
Total expense for the period	12	22
Other Project [Member]
Total expense for the period	$ 72	$ 535